Sorry, that's not right.  The placental barrier protects the developing and sensitive fetus from most toxicants distributed in the maternal circulation. This barrier consists of several cell layers between the maternal and fetal circulatory vessels in the placenta. Lipids in the cell membranes limit the diffusion of water-soluble toxicants. Toxicants that are lipid soluble are more likely to penetrate through the placenta than water-soluble toxicants.